The present invention relates generally to an acoustic transducer or loudspeaker and, more particularly, to planar loudspeakers for use in suspended ceilings.
Advances in dynamic loudspeakers have been provided by the advent of planar diaphragm loudspeakers. Examples of such planar loudspeakers are shown and described in U.S. Pat. Nos. 4,003,449 and 4,997,058, both issued in the name of Jose J. Bertagni. Further examples are described in U.S. Pat. Nos. 5,425,107, 5,539,835 and 5,693,917 issued to Alejandro Bertagni et al.
Planar loudspeakers can be manufactured in various shapes and sizes, and used in a multitude of applications. For example, planar loudspeakers have been used in suspended ceiling structures of the type found in commercial buildings. Such suspended ceilings typically comprise a series of metallic runners and tees forming a 2′×2′ or 2′×4′ grid onto which multiple acoustic ceiling tiles are placed, allowing for a uniform, uninterrupted surface appearance. When used in commercial ceiling structures, advantages by planar diaphragm loudspeakers over loudspeakers utilizing conventional cone-type diaphragms include greater dispersion of sound, economy of manufacture, ease of installation and improved aesthetic appearance. Conventional, cone-type loudspeakers have been used in commercial ceiling structures for decades. Their intended applications encompass paging, background or foreground music. Such cone-type devices require a metallic or plastic grille in the front side in order to conceal the cone—and in certain cases its hardware or a ported hole—from plain sight. Such grille is often perceived as visually unpleasant and also disrupts the continuity of the ceiling surface.
In prior planar loudspeaker approaches, two-dimensional representations have been used to mimic three-dimensional surface textures. For example, it has been previously known to have planar loudspeakers in the apparent shape of a ceiling tile which have a painted or screen-printed front surface in order to match the color and/or pattern design of the surrounding ceiling tiles, giving the installation an unobtrusive look. It is also known that a pre-printed sheet of paper can be applied over the front surface of the loudspeaker to obtain similar aesthetic results. Such example has been disclosed in U.S. Pat. Nos. 3,596,733 and 3,779,336, both issued to Jose J. Bertagni. It has also been known to have planar loudspeakers with a stretched, pre-printed fabric over the exposed front surface of the diaphragm. Such fabric is to be used for decorative purposes, and could also be screen-printed to match certain ceiling tile patterns. Such example is described in U.S. Pat. Nos. 3,596,733 and 3,779,336, both issued in the name of Jose J. Bertagni.
A recent interpretation of the latter is found in U.S. Pat. No. 6,386,315 issued to Kenneth P. Roy et al., though the fabric is stretched in front of the diaphragm but not in contact with its surface, therefore narrowing the application to acoustically transparent fabrics and therefore limiting its advantage. Although the surface finishes abovementioned have been used in commerce, they are limited to a two-dimensional representation of a three-dimensional surface, which in many cases is not completely adequate or, even more, not substantially similar to the surrounding surface of the ceiling where the loudspeaker is intended to be installed.
A further known concept is a planar-type loudspeaker with a sheet of pre-molded polymer material bonded against the front surface of the loudspeaker, intended to simulate a ceiling tile. Although it could be considered as an improvement over two-dimensional methods previously cited, the added mass and rigidity of such sheet and the lamination effect caused by the bond between the diaphragm and the decorative sheet drastically deteriorates the overall performance of the loudspeaker. The foregoing, along with the added material cost, does not seem to provide an advantage over previous embodiments. Such example can be found in U.S. Pat. No. 4,928,312 issued to Amel Hill.
Yet, a further known method provides for molding the front surface of the diaphragm to take on the appearance of an acoustic tile, permitting unobtrusive installation of the loudspeaker in ceilings of commercial structures formed of like-appearing ceiling tiles. See U.S. Pat. Nos. 5,425,107, 5,539,835 and 5,693,917 issued to Alejandro Bertagni et al. This alternative does not affect the performance of the planar loudspeaker, and it is more cost-effective than the method described in U.S. Pat. No. 4,928,312 cited above, it does limit the ability to adapt the loudspeaker's appearance for a variety of acoustic tile configurations. Nonetheless, these prior approaches have a number of shortfalls, including sound reproduction, manufacturing and material costs, and integration into the ceiling.
Accordingly, there is a need for a planar diaphragm loudspeaker for use in a suspended ceiling grid that overcomes the aforementioned difficulties and allows for unobtrusive integration. The present invention fulfills this need.